Communications device, infrastructure equipment, wireless communications network and methods

ABSTRACT

A user terminal configured to perform communication with an infrastructure equipment of a mobile communications network. The user terminal including a receiver configured to receive signals transmitted by the infrastructure equipment in accordance with a wireless access interface and a transmitter configured to transmit signals to the infrastructure equipment in accordance with the wireless access interface. The user terminal is configured to receive an indication on a downlink of the wireless access interface of one of a plurality of different subcarrier spacing which the communications device should use to transmit or to receive the signals representing the data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/207,215. filed Dec. 3, 2018, which is a continuation of U.S.application Ser. No. 15/835,499, filed Dec. 8, 2017 (now U.S. Pat. No.10,182,443), which is a continuation of U.S. application Ser. No.15/615,511, filed Jun. 6, 2017 (now U.S. Pat. No. 9,867,191), which is acontinuation of International Application No. PCT/EP2016/082762, filedDec. 28, 2016, which claims priority to European patent application16150823.9, filed Jan. 11, 2016, the contents of each are hereinincorporated by reference.

BACKGROUND

The present application claims the Paris convention priority of Europeanpatent application 16150823.9, the contents of which are incorporatedherein by reference.

Field of Disclosure

The present disclosure relates to communications devices, which areconfigured to transmit uplink signals to and/or receive downlink signalsfrom an infrastructure equipment of a mobile communications network viaa wireless access interface, which is configured to include on theuplink a plurality of different subcarrier spacings. The presenttechnique also relates to infrastructure equipment and methods ofcommunicating.

Description of Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

Third and fourth generation wireless communications systems, such asthose based on the third generation project partnership (3GPP) definedUMTS and Long Term Evolution (LTE) architecture are able to supportsophisticated services such as instant messaging, video calls as well ashigh speed intemet access. For example, with the improved radiointerface and enhanced data rates provided by LTE systems, a user isable to enjoy high data rate applications such as mobile video streamingand mobile video conferencing that would previously only have beenavailable via a fixed line data connection. The demand to deploy thirdand fourth generation networks is therefore strong and the coverage areaof these networks, i.e. geographic locations where access to thenetworks is possible, is expected to increase rapidly. However, whilstfourth generation networks can support communications at high data rateand low latencies from devices such as smart phones and tabletcomputers, it is expected that future wireless communications networkswill need to support communications to and from a much wider range ofdevices, including reduced complexity devices, machine typecommunication devices, devices which require little or no mobility, highresolution video displays and virtual reality headsets. As such,supporting such a wide range of communications devices can represent atechnical challenge for a wireless communications network.

A current technical area of interest to those working in the field ofwireless and mobile communications is known as “The Internet of Things”or IoT for short. The 3GPP has proposed to develop technologies forsupporting narrow band (NB)-IoT using an LTE or 4G wireless accessinterface and wireless infrastructure. Such IoT devices are expected tobe low complexity and inexpensive devices requiring infrequentcommunication of relatively low bandwidth data. It is also expected thatthere will be an extremely large number of IoT devices which would needto be supported in a cell of the wireless communications network.Furthermore such NB-IoT devices are likely to be deployed indoors and/orin remote locations making radio communications challenging.

SUMMARY OF THE DISCLOSURE

According to one example embodiment of the present technique, acommunications device is configured to transmit signals to and/orreceive signals from an infrastructure equipment of a mobilecommunications network. The communications device comprises a receiver,a transmitter and a controller. The receiver is configured to receivesignals transmitted by the infrastructure equipment in accordance with awireless access interface, the transmitter is configured to transmitsignals to the infrastructure equipment in accordance with the wirelessaccess interface, and the controller is configured to control thetransmitter and the receiver to transmit data to the infrastructureequipment via an uplink of the wireless access interface or to receivedata on the downlink of the wireless access interface. The wirelessaccess interface can provide a plurality of different spacings ofsubcarriers for transmitting signals representing the data on the uplinkor for receiving the signals representing the data on the downlink. Thecontroller is configured in a combination with the transmitter and thereceiver, when the infrastructure equipment identifies a requirement toprovide communications resources of the wireless access interface on theuplink for the communications device to transmit data to theinfrastructure equipment or on the downlink for the communicationsdevice to receive data from the infrastructure equipment, to receive anindication on a downlink of the wireless access interface of one of theplurality of different subcarrier spacings which the communicationsdevice should use to transmit or to receive the signals representing thedata, the indicated subcarrier spacing also determining whether thecommunications device should use a single subcarrier or multiplesubcarriers.

Embodiments of the present technique can provide an arrangement in whicha subcarrier spacing can be selected for a communications device by theinfrastructure equipment in response to a request for communicationsresources, which can be restricted for single subcarrier operation,which although reducing a data communications bandwidth compared to amultiple subcarrier allocation can increase a range for wirelesscommunications by increasing a power spectral density of the transmittedsignal. Accordingly improved uplink communications can be provided forexample for communications devices located indoors.

According to another example embodiment of the present technique, thereis provided a communications device configured to transmit signals toand/or receive signals from an infrastructure equipment of a mobilecommunications network. The communications device comprises a receiverconfigured to receive signals transmitted by the infrastructureequipment in accordance with a wireless access interface, a transmitterconfigured to transmit signals to the infrastructure equipment inaccordance with the wireless access interface, and a controllerconfigured to control the transmitter and the receiver to transmit datato the infrastructure equipment via an uplink of the wireless accessinterface or to receive data on the downlink of the wireless accessinterface. The wireless access interface includes communicationsresources for allocation to the communications device on the uplink andthe downlink, the communications resources comprising frequencyresources of a predetermined number of subcarriers, one or more of whichcan be allocated to the communications device, and time resources inwhich the wireless access interface is divided into predetermined timeunits. The communications device is configured, when the infrastructureequipment identifies a requirement to provide communications resourcesof the wireless access interface on the uplink or on the downlink, toreceive an indication on a downlink of the wireless access interface ofone or more of the subcarriers allocated to the communications devicefor receiving or transmitting the data, and a transmission time intervalrepresenting a number of the time units within which a transport blockof the data is to be transmitted or to be received, and the transmissiontime interval can vary as a number of the time units as a function ofallocated communications resource, for example, the number of the one ormore subcarriers allocated to the communications device.

Embodiments of a further aspect of the present technique can provide anarrangement of a communications device and an infrastructure equipmentto signal efficiently an indication of a transmission time interval witha number of subcarriers which have been allocated to the communicationsdevice, because for a given transport block, the transmission timeinterval can vary depending on, for example, a number of one or moresubcarriers of a wireless access interface which have been allocated tothe communications device out of a predetermined maximum. Exampletechniques for signalling the transmission time interval according tothe embodiments presented below, can provide an efficient use ofcommunications resources to indicate to the communications device thetransmission time interval which is to be used.

Further respective aspects and features are defined by the appendedclaims.

The foregoing paragraphs have been provided by way of generalintroduction, and are not intended to limit the scope of the followingclaims. The described embodiments, together with further advantages,will be best understood by reference to the following detaileddescription taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings wherein likereference numerals designate identical or corresponding parts throughoutthe several views, and wherein:

FIG. 1 is a schematic block diagram illustrating an example of a mobiletelecommunication system:

FIG. 2 is a schematic representation illustrating a frame structure of adown-link of a wireless access interface according to an LTE standard;

FIG. 3 is a schematic representation illustrating a frame structure ofan up-link of wireless access interface according to an LTE standard;

FIG. 4 is a part schematic block diagram of a communications device andan infrastructure equipment, part message flow diagram illustrating aprocess of granting uplink resources to the communications device andindicating a subcarrier spacing which should be used according to thepresent technique;

FIG. 5 is a schematic illustration showing how a single bit field can beused to indicate either a 3.75 kHz subcarrier spacing or a 15 kHzsubcarrier spacing; and

FIG. 6 is a flow diagram illustrating an example process in which acommunications device detects a subcarrier spacing selected by aninfrastructure equipment of a wireless communications network accordingto the present technique;

FIG. 7 is a schematic block diagram presenting the downlink framestructure shown in FIG. 2 but also showing a transmission of a transportblock within one physical resource block of an LTE wireless accessinterface;

FIG. 8 is a schematic representation of different transmission timeinterval (TTI) lengths which change in accordance with the number ofsubcarriers for four different examples of subcarriers allocated to acommunications device by an infrastructure equipment;

FIG. 9 is a schematic block diagram illustrating three different lengthsof transmission time interval (TTI) resulting from three differentexamples of subcarrier allocations; and

FIG. 10 is a schematic block diagram illustrating an arrangement betweenan infrastructure equipment and a communications device according to thepresent technique in which a downlink control message allocatesresources on the downlink and provides an indication implicitly orexplicitly of a transmission time interval length to use.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Conventional Communications System

FIG. 1 provides a schematic diagram illustrating some basicfunctionality of a mobile telecommunications network/system 100operating in accordance with LTE principles and which may be adapted toimplement embodiments of the disclosure as described further below.Various elements of FIG. 1 and their respective modes of operation arewell-known and defined in the relevant standards administered by the3GPP (RTM) body, and also described in many books on the subject, forexample, Holma H. and Toskala A [1]. It will be appreciated thatoperational aspects of the telecommunications network which are notspecifically described below may be implemented in accordance with anyknown techniques, for example according to the relevant standards.

The network 100 includes a plurality of base stations 101 connected to acore network 102. Each base station provides a coverage area 103 (i.e. acell) within which data can be communicated to and from communicationsdevices 104. Data is transmitted from base stations 101 tocommunications devices 104 within their respective coverage areas 103via a radio downlink. Data is transmitted from communications devices104 to the base stations 101 via a radio uplink. The uplink and downlinkcommunications are made using radio resources that are licenced forexclusive use by the operator of the network 100. The core network 102routes data to and from the communications devices 104 via therespective base stations 101 and provides functions such asauthentication, mobility management, charging and so on. Communicationsdevices may also be referred to as mobile stations, user equipment (UE),user device, mobile radio, and so forth. Base stations may also bereferred to as transceiver stations/NodeBs/eNodeBs (eNB for short), andso forth.

Wireless communications systems such as those arranged in accordancewith the 3GPP defined Long Term Evolution (LTE) architecture use anorthogonal frequency division modulation (OFDM) based interface for theradio downlink (so-called OFDMA) and a single carrier frequency divisionmultiple access scheme (SC-FDMA) on the radio uplink.

FIG. 2 provides a simplified schematic diagram of the structure of adownlink of a wireless access interface that may be provided by or inassociation with the eNB of FIG. 1 when the communications system isoperating in accordance with the LTE standard. In LTE systems thewireless access interface of the downlink from an eNB to a UE is basedupon an orthogonal frequency division multiplexing (OFDM) access radiointerface. In an OFDM interface the resources of the available bandwidthare divided in frequency into a plurality of orthogonal subcarriers anddata is transmitted in parallel on a plurality of orthogonalsubcarriers, where bandwidths between 1.25MHZ and 20MHz bandwidth may bedivided into 128 to 2048 orthogonal subcarriers for example. Eachsubcarrier bandwidth may take any value but in LTE it is conventionallyfixed at 15KHz. However it has been proposed in the future [2][3] toprovide also a reduced subcarrier spacing of 3.75 kHz for certain partsof the LTE wireless access interface for both the uplink and thedownlink. As shown in FIG. 2, the resources of the wireless accessinterface are also temporally divided into frames where a frame 200lasts 10ms and is subdivided into 10 subframes 201 each with duration of1 ms. Each subframe is formed from 14 OFDM symbols and is divided intotwo slots each of which comprise six or seven OFDM symbols depending onwhether a normal or extended cyclic prefix is being utilised betweenOFDM symbols for the reduction of inter symbol interference. Theresources within a slot may be divided into resources blocks 203 eachcomprising 12 subcarriers for the duration of one slot and the resourcesblocks further divided into resource elements 204 which span onesubcarrier for one OFDM symbol, where each rectangle 204 represents aresource element. More details of the down-link structure of the LTEwireless access interface are provided in Annex 1.

FIG. 3 provides a simplified schematic diagram of the structure of anuplink of an LTE wireless access interface that may be provided by or inassociation with the eNB of FIG. 1. In LTE networks the uplink wirelessaccess interface is based upon a single carrier frequency divisionmultiplexing FDM (SC-FDM) interface and downlink and uplink wirelessaccess interfaces may be provided by frequency division duplexing (FDD)or time division duplexing (TDD), where in TDD implementations subframesswitch between uplink and downlink subframes in accordance withpredefined patterns. However, regardless of the form of duplexing used,a common uplink frame structure is utilised. The simplified structure ofFIG. 3 illustrates such an uplink frame in an FDD implementation. Aframe 300 is divided in to 10 subframes 301 of 1 ms duration where eachsubframe 301 comprises two slots 302 of 0.5 ms duration. Each slot isthen formed from seven OFDM symbols 303 where a cyclic prefix 304 isinserted between each symbol in a manner equivalent to that in downlinksubframes. In FIG. 3 a normal cyclic prefix is used and therefore thereare seven OFDM symbols within a subframe, however, if an extended cyclicprefix were to be used, each slot would contain only six OFDM symbols.The resources of the uplink subframes are also divided into resourceblocks and resource elements in a similar manner to downlink subframes.More details of the LTE up-link represented in FIG. 3 are provided inAnnex 1.

Narrowband Internet of Things

Embodiments of the present technique can provide an arrangement in whicha mobile communications device or UE 104 can operate to communicate in awireless communications system via a base station or infrastructureequipment. A communications device is configured to transmit signalsrepresenting data to the infrastructure equipment on an uplink of awireless access provided by the infrastructure equipment or to receivesignals representing the data on a downlink of the wireless accessinterface from the infrastructure equipment. The wireless accessinterface can provide a plurality of different spacings of subcarriersfor transmitting or receiving the signals representing the data. Thecommunications device is configured to receive an indication on adownlink of the wireless access interface of one of the plurality ofdifferent subcarrier spacings which the communications device should useto transmit or to receive the signals representing the data, theindicated subcarrier spacing also determining whether the communicationsdevice should use a single subcarrier or multiple subcarriers. As such asubcarrier spacing can be selected for the communications device by theinfrastructure equipment which can be restricted for single subcarrieroperation, which although reducing a data communications bandwidthcompared to a multiple subcarrier allocation can increase a range forwireless communications by increasing a power spectral density of thetransmitted signal. As explained above, this arrangement can provide animprovement in uplink communications for remotely located and/or indoordevices, particularly those which have a reduced complexity andtherefore lower performance transmitter or indeed limited transmissionpower.

As explained above, it has been proposed to develop an adaptation of amobile communications network to accommodate narrow band communicationswithin an existing wireless access interface which has been developed toprovide broadband wireless communications. For example, in 3GPP aproject relating to improvements to LTE wireless access interfaces toprovide for a Narrowband Internet of Things (NB-IoT) was agreed [2].This project is aimed at improved indoor coverage, support for massivenumber of low throughput devices, low delay sensitivity, ultra-lowdevice cost, low device power consumption and (optimised) networkarchitecture. An example of such a device is a smart meter. It has beenproposed that an NB-IoT communications system supports a bandwidth ofonly 180 kHz and can have three operational modes:

-   -   1. ‘Stand-alone operation’ utilizing for example the spectrum        currently being used by GERAN systems as a replacement of one or        more GSM carriers    -   2. ‘Guard band operation’ utilizing the unused resource blocks        within a LTE carrier's guard-band    -   3. ‘In-band operation’ utilizing resource blocks within a normal        LTE carrier

In known LTE systems the smallest uplink resource granularity is onephysical resource block (PRB), which comprises twelve subcarriers.However it has been proposed in [3], that a finer uplink resourcegranularity can be provided where the uplink signal can be transmittedin a single tone (single subcarrier) or multi-tones (multiplesubcarriers). Single tone transmission allows the UE to concentrate(i.e. PSD boost) its power onto a single subcarrier, which can provide agreater transmission range for transmitted signals. This is beneficialfor large coverage enhancement operations. However, single tonetransmission can only carry a small amount of information since the(frequency) resource is limited. On the other hand, multi-tonetransmission occupying several subcarriers (up to an entire PRB) hasmore resources but the power is spread among multiple subcarriers andtherefore it has a shorter range compared to that of a single tonetransmission. Using single tone transmission would increase the capacityof the system, because it allows more UEs to access the wireless accessinterface simultaneously. According to the present technique therefore acontroller or scheduler in the eNB can provide resources of the wirelessaccess interface with greater flexibility since the scheduler canallocate the resources with a finer granularity.

Signalling the Subcarrier Spacing

According to an example embodiment of the present technique, a UE cantransmit uplink data using a sub-carrier as a single tone, which can betransmitted as one of two different subcarrier spacings depending on thedecision of the infrastructure equipment. Note that the term “subcarrierspacing” is applicable for both multi-tone and single-tone transmission:for the case of single-tone transmissions, it relates to the spacingbetween subcarriers of transmissions from different UEs. According toone example the subcarrier spacing can be either 3.75 kHz or 15 kHz.Multi-subcarrier/multi-tone transmission is only supported when there isa 15 kHz subcarrier spacing. The 3.75 kHz single tone transmission hasan advantage over the 15 kHz subcarrier spacing in that the powerspectral density is boosted, leading to longer range transmission. Inother examples the 15 kHz subcarrier spacing can mitigate its shortertransmission range by signal repetition, leading to an increased range,but with the disadvantage of supporting a lower data rate (due to therepetition of the signal). However with the availability of two possiblesubcarrier spacings and modes of transmission (single tone on a singlesubcarrier, or multiple tones via multiple subcarriers) there is a needto provide an arrangement for informing the UE of the subcarrier spacingit should use, the mode of transmission (single or multiple subcarriers)and indeed the location of the subcarrier(s).

According to one proposal, after the first random access message, whichmight include a preamble identifying the UE, the first uplink messagefrom the UE would at least be transmitted using single tone. The eNBwould therefore be configured to receive the first uplink message as asingle tone transmission. Since there maybe two types of single tonetransmission, with different subcarrier spacing, the UE needs to knowwhich single tone transmission should be used.

Furthermore it would also benefit the eNB if single tone or multi tonetransmission can be indicated dynamically. According to the presenttechnique therefore, the eNB can signal the subcarrier spacing, whichshould be used by the UE, in an uplink grant message. Typically, theuplink grant message includes scheduling information such as anindication of the frequency resource, time resource (if repetition isused) and the modulation and coding scheme (MCS), which should be used.According to the present technique, a new indicator is introduced whichinforms the UE of the subcarrier spacing, which should be used, forexample whether to use 3.75 kHz or 15 kHz subcarrier spacing. For theexample of LTE, the uplink grant message is carried by the DownlinkControl Information (DCI), which is transmitted via a downlink controlchannel, which is a PDCCH (or a narrow band (NB)-PDCCH). In anotherexample, the uplink grant message carrying this scheduling informationcan also be carried by the Random Access Response (RAR) during a randomaccess process.

FIG. 4 provides an example block diagram of a communications device orUE 104 and a base station or eNB 101 performing a message exchange inaccordance with an embodiment of the present technique, in which the eNBsignals the subcarrier spacing which should be used by a UE 104 totransmit data on the uplink to the eNB. As shown in FIG. 4, a UE 104includes a transmitter 401 and a receiver 402 which are controlled by acontroller 403. Correspondingly, the eNB 101 includes a transmitter 411and a receiver 412 which are controlled by a controller 413 which can bereferred to as a scheduler. As explained above, the UE 104 transmits andreceives signals to and from the eNB 101 via a wireless access interfaceprovided by the eNB as part of the wireless communications network. Inaccordance with the present technique, the UE 104 is provided with anindication of a subcarrier spacing to use which also implies whether theallocated resources for transmitting data on the uplink to the eNB 101is for a single subcarrier or for multiple sub carriers.

FIG. 4 also illustrates a message exchange between the UE 104 and theeNB 101 providing three examples 416, 417, 418 of events during whichthe eNB can signal to the UE the subcarrier spacing which should beused. The UE 104 also receives an indication from the eNB 101 of whetherthe uplink resource is for a single subcarrier or multiple subcarriersand also a frequency resource allocation identifying the subcarrierwhich should be used or the multiple subcarriers which should be useddepending upon the subcarrier spacing selected by the eNB 101. In afirst example 416 the random access response message transmitted on thePDSCH includes a field 430 which identifies the subcarrier spacing to beused and in a field 432 the frequency resources to be used. Depending onwhether the subcarrier spacing indicates 3.75 kHz or 15 kHz, the UE 104interprets the frequency resource field differently, in which the UE 104is signalled to use a subcarrier spacing.

As shown in FIG. 4, the communications device 104 first transmits apreamble 420 via a PRACH channel in accordance with a conventionalrandom access procedure. As part of the random access procedure the eNB101 transmits a random access response message 434 via the PDSCH whichis scheduled by transmitting a DCI message 422 on the PDCCH. There thenfollows a procedure (not shown) in which the UE 104 requests uplinkresources by establishing an RRC connection. The random access responsemessage 434 is transmitted in the PDSCH and the following messagesassociated with RRC connection setup are transmitted via PDSCH and PUSCH(e.g. an RRC connection setup request message is transmitted via PUSCHand an RRC connection setup message is transmitted via PDSCH). For thisexample 416, the uplink grant in the RAR messages can include a fieldindicating the subcarrier spacing 430 and a frequency resources field432. Depending on the value of the field 430 indicating the subcarrierspacing, the UE 104 interprets the frequency resource field 432differently as will be explained in the paragraphs below. Therefore, ifthe subcarrier spacing field 430 indicates that the allocated subcarrierspacing is only for a single carrier operation then the UE 104interprets the frequency resource field 432 as an allocation of a singlesubcarrier identified by a number of that subcarrier spacing. Incontrast if the sub carrier spacing 430 can be for single or multiplesubcarriers, then the frequency resource field 432 provides anindication of a frequency band providing a plurality of subcarriers.

In the second example 417 the UE transmits a buffer status report 440 inthe uplink on a PUSCH to the eNB 101. The UE may transmit several bufferstatus report messages, which may be transmitted periodically to informthe eNB of the amount of data which is present in a buffer of the UE 104(not shown in FIG. 4 but see FIG. 10). In accordance with predeterminedcriteria set in the controller 413, the controller 413 decides to grantuplink resources to the UE 104 to transmit data from the UE's buffer onthe uplink. Accordingly, the eNB 101 transmits a DCI message 442 whichincludes a field 444 identifying the subcarrier spacing to be used andthe frequency resources which the UE should use on the uplink 446. Thesubcarrier spacing field 444 and the frequency resource field 446provide the same information as the subcarrier field 430 and thefrequency resources field 432 in the Random Access Response messagestransmitted in the first example 416.

As a third example 418 the eNB 101 has data to transmit to the UE 104 onthe downlink. In accordance with a conventional arrangement, if the UE104 is currently in an idle mode then a paging message 450 istransmitted to the UE 104 in order to instruct the UE to switch to anactive mode, and to receive an allocation of communications resources onthe downlink for the UE 104 to receive the data. In this embodiment, thepaging message contains information for subcarrier spacing 454.Essentially, the subcarrier spacing field 454 and the frequency resourcefield 454 provide the same information as the subcarrier spacing field430, 444 and the frequency resource field 432, 446 for the first andsecond examples 417, 418.

The examples above show how a subcarrier spacing field 430,444 andfrequency resource field 432, 446 can be used to define the subcarrierspacing and frequency resources applied in the uplink. It will beapparent to a skilled artisan how in a similar manner, a subcarrierspacing field 424 and a frequency resources field 426 could also beapplied to define the subcarrier spacing and frequency resources usedfor a downlink transmission 434.

The specification in each of the respective subcarrier spacing field424, 430, 444, 454 and frequency resource field 426, 432, 446, 456 willbe explained in the following paragraphs with several examples.

The examples above show how a subcarrier spacing field 430,444 andfrequency resource field.

According to an example embodiment, as illustrated above, the subcarrierspacing field can be a single bit in the DCI for indicating whether theuplink transmission uses a 3.75 kHz or 15 kHz subcarrier spacing.

According to a conventional arrangement control messages transmitted viathe PDCCH or NB-PDCCH need to be blindly decoded by the UE. Typically toreduce the number of blind decodes, a common DCI format or DCI size isused. For a Narrow Band Internet of Things, a common DCI may be used toschedule a 3.75 kHz single tone transmission and 15 kHz single ormulti-tone transmissions. Therefore, in another embodiment, when theindication provided in the DCI indicates that a 3.75 kHz subcarrierspacing should be used, a frequency resource field in the uplink grantis used to indicate one of 48 subcarriers. On the other hand, if thecontrol message indicates a 15 kHz subcarrier spacing, the number ofsubcarriers available for allocation is twelve, which can be single toneor multiple tones allocations, and the frequency resource field canindicated an allocation of for example 1, 2, 4, 8 or 12 subcarriers. Assuch, in accordance with the subcarrier spacing which is selected, theinterpretation of the frequency resource field 432, 446 is different asshown in FIG. 5.

FIG. 5 provides a schematic illustration of an example of twopredetermined subcarrier spacing of 3.75 kHz and 15 kHz. The lines 500on the right hand side represent the subcarriers for 15 kHz spacingwhereas lines 502 on the left hand side of the diagram representsubcarrier spacing for 3.75 kHz. In one example, a single bit representsthe subcarrier spacing selected, for example, a value of “0”representing a 3.75 kHz spacing or a value of “1” representing a 15 kHzspacing.

An example flow chart, illustrating a process in which the UE interpretsa control message from an eNB, such as a “single-tone/subcarrier spacingbit” indicator in a DCI message is shown in FIG. 6. The processrepresented by the flow diagram shown in FIG. 6 is summarised asfollows:

S1: The receiver 402 under the control of the controller 403 within theUE 104 first extracts the single bit representing the subcarrier spacingas either 3.75 kHz or 15 kHz from, for example, a narrow band PDCCH.

At decision point S2, the controller determines whether the subcarrierspacing bit or single tone bit is set to indicate a 3.75 kHz subcarrierspacing. If the bit is set to indicate a 3.75 kHz subcarrier spacingthen processing proceeds to step S4. Otherwise, processing proceeds tostep S6 for a 15 kHz subcarrier spacing.

S4: If the single bit indicating the subcarrier spacing of 3.75 kHz isset, then the next frequency resource field 432, 446 is interpreted asindicating a single subcarrier at a particular location within thefrequency band using numerical rules for 3.75 kHz subcarrier spacing.

S6: If the bit representing the selected subcarrier spacing is set toindicate a 15 kHz subcarrier spacing then the frequency resource field432, 446 is interpreted in accordance with numerical rules to representa single or a multiple carrier allocation.

S8: The UE then proceeds to transmit signals via the allocatedsubcarrier or multiple subcarriers according to the configurationallocated by the frequency resource field. Furthermore, other schedulinginformation may indicate other communications parameters such as themodulation coding scheme or transport block size etc.

An example illustration of how the eNB 101 can communicate to the UE 104in accordance with a predetermined arrangement identifying the meaningof the “frequency resource field” 432, 446 is shown in Table 1. In thisexample, the frequency resource field has a different interpretationdepending on the “subcarrier spacing bit” (equivalent to the“single-tone bit” of step S1 in FIG. 6) indicating whether thesub-carrier spacing is 3.75 kHz or 15 kHz. Depending on the value of thesub-carrier spacing indicator:

-   -   If the subcarrier spacing is indicated as 3.75 kHz, then the        “frequency resource field” directly indicates the single tone to        be used for the uplink transmission.    -   If the subcarrier spacing is indicated as 15 kHz, then the        “frequency resource field” indicates the starting subcarrier and        the number of consecutive subcarriers to be used for the 15 kHz        numerology transmission: either a single tone transmission or a        multi-tone transmission. The starting subcarrier locations of        the multi-tone transmissions are a multiple of the number of        tones used for the 3.75 kHz single-tone transmission.

TABLE 1 Example meaning of the “frequency resource field” according toan embodiment of the invention Meaning of “subcarrier spacing bit”“frequency “subcarrier spacing “subcarrier spacing resource field” bit”= 3.75 kHz bit” = 15 kHz  0: 000000 Subcarrier 0 Subcarrier 0; 1 tone 1: 000001 Subcarrier 1 Subcarrier 1; 1 tone  2: 000010 Subcarrier 2Subcarrier 2; 1 tone  3: 000011 Subcarrier 3 Subcarrier 3; 1 tone  4:000100 Subcarrier 4 Subcarrier 4; 1 tone  5: 000101 Subcarrier 5Subcarrier 5; 1 tone . . . . . . . . . 11: 001011 Subcarrier 11Subcarrier 11; 1 tone 12: 001100 Subcarrier 12 Subcarrier 0; 2 tones 13:001101 Subcarrier 13 Subcarrier 2; 2 tones 14: 001110 Subcarrier 14Subcarrier 4; 2 tones . . . . . . . . . 17: 010001 Subcarrier 17Subcarrier 10; 2 tones 18: 010010 Subcarrier 18 Subcarrier 0; 4 tones19: 010011 Subcarrier 19 Subcarrier 4; 4 tones 20: 010100 Subcarrier 20Subcarrier 8; 4 tones 21: 010101 Subcarrier 21 Subcarrier 0; 8 tones 22:010110 Subcarrier 22 Subcarrier 4; 8 tones 23: 010111 Subcarrier 23Subcarrier 0; 12 tones . . . . . . N/A 47: 101111 Subcarrier 47 N/A . .. N/A N/A 63: 111111 N/A N/A

Another example of the table is shown in Table 2. The “reserved” fieldsin this table 2 can be used to signal for purposes other than frequencyresource indication. For example the field could be used to signal a“PDCCH order”, where the PDCCH order provides a procedure for the eNB tosend a message to the UE directly using lower layer signalling, i.e.below MAC layer, or could be used to enhance the error detectioncapability of the PDCCH message. This is because, if the UE receives oneof a plurality of reserved values, it ignores the contents of the PDCCH.In this example, the frequency resource field also has a differentinterpretation depending on the “subcarrier spacing bit” indication:

-   -   For 3.75 kHz, the “frequency resource field” directly indicates        the single tone to be used for the uplink transmission. In this        table, only a subset of the possible single tone transmissions        are allowed. The example shows that every second single tone        transmission at 3.75 kHz is allowed. This restriction in the        number of single tone transmissions may limit the number of UEs        that can be simultaneously assigned, but this is not a        significant concern if the system is not uplink capacity        limited. By allowing 3.75 kHz single tone transmissions to be        signalled throughout the system bandwidth, scheduler flexibility        is maintained.    -   For 15 kHz, the “frequency resource field” indicates the        starting subcarrier and the number of consecutive subcarriers to        be used for the 15kHz numerology transmission either a single        tone transmission or a multi-tone transmission. The starting        subcarrier locations of the multi-tone transmissions are a        multiple of the number of tones used for the 3.75 kHz        single-tone transmission.

TABLE 2 Example meaning of the “frequency resource field” Meaning of“subcarrier spacing bit” “frequency “subcarrier spacing “subcarrierspacing resource field” bit” = 3.75 kHz bit” = 15 kHz  0: 000000Subcarrier 0 Subcarrier 0; 1 tone  1: 000001 Subcarrier 2 Subcarrier 1;1 tone  2: 000010 Subcarrier 4 Subcarrier 2; 1 tone  3: 000011Subcarrier 8 Subcarrier 3; 1 tone  4: 000100 Subcarrier 10 Subcarrier 4;1 tone  5: 000101 Subcarrier 12 Subcarrier 5; 1 tone . . . . . . . . .11: 001011 Subcarrier 22 Subcarrier 11; 1 tone 12: 001100 Subcarrier 24Subcarrier 0; 2 tones 13: 001101 Subcarrier 26 Subcarrier 2; 2 tones 14:001110 Subcarrier 28 Subcarrier 4; 2 tones . . . . . . . . . 17: 010001Subcarrier 34 Subcarrier 10; 2 tones 18: 010010 Subcarrier 36 Subcarrier0; 4 tones 19: 010011 Subcarrier 38 Subcarrier 4; 4 tones 20: 010100Subcarrier 40 Subcarrier 8; 4 tones 21: 010101 Subcarrier 42 Subcarrier0; 8 tones 22: 010110 Subcarrier 44 Subcarrier 4; 8 tones 23: 010111Subcarrier 46 Subcarrier 0; 12 tones 24 −> 31 reserved reserved

In another embodiment of the invention, there is no explicit “subcarrierspacing bit” indication in the PDCCH, but the “uplink transmissionconfiguration” i.e. use of a single-tone and the configuration of asingle tone or multi-tone is determined directly from the table. Anexample of this signalling is shown in Table 3. In this table, there isa restricted number of possible configurations for the 3.75 kHz singletone transmission. In this case, the 3.75 kHz single tone transmissionsoccupy a group of consecutive subcarriers in the lower portion of thefrequency resource space. A restricted number of 3.75 kHz single tonetransmissions may be adequate when it is considered that only aproportion e.g. 5% of the devices in the cell experience extremecoverage conditions so that only that limited number need the 3.75 kHzsingle tone transmission and the other devices can be serviced with 15kHz single or multi-tone transmissions.

TABLE 3 Example meaning of the “frequency resource field” according toan embodiment of the invention “uplink transmission Physicalconfiguration of uplink configuration” resources  0: 000000 15 kHz;Subcarrier 0; 1 tone  1: 000001 15 kHz; Subcarrier 1; 1 tone  2: 00001015 kHz; Subcarrier 2; 1 tone  3: 000011 15 kHz; Subcarrier 3; 1 tone  4:000100 15 kHz; Subcarrier 4; 1 tone  5: 000101 15 kHz; Subcarrier 5; 1tone . . . . . . 11: 001011 15 kHz; Subcarrier 11; 1 tone 12: 001100 15kHz; Subcarrier 0; 2 tones 13: 001101 15 kHz; Subcarrier 2; 2 tones 14:001110 15 kHz; Subcarrier 4; 2 tones . . . . . . 17: 010001 15 kHz;Subcarrier 10; 2 tones 18: 010010 15 kHz; Subcarrier 0; 4 tones 19:010011 15 kHz; Subcarrier 4; 4 tones 20: 010100 15 kHz; Subcarrier 8; 4tones 21: 010101 15 kHz; Subcarrier 0; 8 tones 22: 010110 15 kHz;Subcarrier 4; 8 tones 23: 010111 15 kHz; Subcarrier 0; 12 tones 24:011000 3.75 kHz; Subcarrier 0 25: 011001 3.75 kHz; Subcarrier 1 26:011010 3.75 kHz; Subcarrier 2 . . . . . . 31: 111111 3.75 kHz;Subcarrier 7

According to another example, all possible configurations of 15 kHzsingle-tone and multi-tone transmissions may be signalled compactly bynoting that there is a limit to the starting tone location when thesystem bandwidth 180 kHz supports twelve 15 kHz subcarriers and thenumber of multi-tones is restricted to {1,2,4,8,12} consecutivemulti-tones. For n_(mt), consecutive multi-tones, and a twelvesubcarrier system bandwidth, the starting 15kHz subcarrier is limited tothe range:start_subcarrier =0→12−n _(mt)

Based on this observation, the possible configurations for the 15 kHzsingle-tone and multi-tone are as shown in Table 4 below. As will beappreciated, the method of signalling 15 kHz single-tone transmissionsfrom this table can be combined with the other methods of signallingidentified in the tables presented above.

TABLE 4 Possible configurations for 15 kHz single- tone and multi-tonetransmissions uplink resource configuration Configuration index Startsubcarrier Number of subcarriers 0 0 1 1 1 1 2 2 1 3 3 1 4 4 1 5 5 1 6 61 7 7 1 8 8 1 9 9 1 10 10 1 11 11 1 12 0 2 13 1 2 14 2 2 15 3 2 16 4 217 5 2 18 6 2 19 7 2 20 8 2 21 9 2 22 10 2 23 0 4 24 1 4 25 2 4 26 3 427 4 4 28 5 4 29 6 4 30 7 4 31 8 4 32 0 8 33 1 8 34 2 8 35 3 8 36 4 8 370 12

In another embodiment, a field in a control channel message indicateswhether the UE is allocated a 3.75 kHz subcarrier-based uplinktransmission or a 15 kHz subcarrier-based uplink transmission and a“frequency and repetition resource field” indicates the subcarrierlocation and number of repetitions that are applied to the transmission.This method of allocation allows the system to signal 15 kHz and 3.75kHz transmissions with equal coverage, noting that repetition of the 15kHz subcarrier signal can extend its coverage until it is comparable tothat of the 3.75 kHz transmission. Other fields in the PDCCH willfurther configure the uplink transmission from the UE. For example, the“frequency and repetition” resource field can indicate a subcarrier andfirst repetition factor, REP1, and one or more of the other fields ofthe PDCCH can indicate another repetition factor, REP2. In this case,the overall repetition to be applied by the UE is:REP _(overall) =REP ₁ ×REP ₂

According to this example embodiment an arrangement is provided whichrecognises that, at the same degree of coverage, more repetition isrequired with a single 15 kHz subcarrier than with a single 3.75 kHzsubcarrier due to the lower power spectral density of the 15 kHzsubcarrier signal.

Table 5 below shows an example mapping between the contents of an indexand the “frequency and repetition resource field”, for the cases wherethe “subcarrier spacing” indication indicates 3.75 kHz and for the casewhere this indication indicates 15 kHz.

TABLE 5 Example meaning of the “frequency and repetition resource field”according to an embodiment of the present technique “frequency Meaningof “subcarrier spacing bit” and repetition “subcarrier spacing“subcarrier spacing resource field” bit” = 3.75 kHz bit” = 15 kHz 0Subcarrier 0 Subcarrier 0; REP1 = 1 1 Subcarrier 1 Subcarrier 0; REP1 =2 2 Subcarrier 2 Subcarrier 0; REP1 = 3 3 Subcarrier 3 Subcarrier 0;REP1 = 4 4 Subcarrier 4 Subcarrier 1; REP1 = 1 5 Subcarrier 5 Subcarrier1; REP1 = 2 6 Subcarrier 6 Subcarrier 1; REP1 = 3 7 Subcarrier 7Subcarrier 1; REP1 = 4 8 Subcarrier 8 Subcarrier 2; REP1 = 1 9Subcarrier 9 Subcarrier 2; REP1 = 2 . . . 40 Subcarrier 40 Subcarrier10; REP1 = 1 41 Subcarrier 41 Subcarrier 10; REP1 = 2 42 Subcarrier 42Subcarrier 10; REP1 = 3 43 Subcarrier 43 Subcarrier 10; REP1 = 4 44Subcarrier 44 Subcarrier 11; REP1 = 1 45 Subcarrier 45 Subcarrier 11;REP1 = 2 46 Subcarrier 46 Subcarrier 11; REP1 = 3 47 Subcarrier 47Subcarrier 11; REP1 = 4

In other examples, the meaning and usage of the “subcarrier spacing” bitcan be configurable by the eNB, for example via system informationbroadcasting SIB signalling. For example, the eNB could signal that the“subcarrier spacing” bit should be interpreted according to a table ofthe form of Table 1 or according to a table of the form of Table 5.

In another embodiment, similar to the frequency resources field, themodulating coding scheme MCS or transport block size TBS would also beinterpreted differently whether a 3.75 kHz or 15 kHz subcarrier spacingis used. If 3.75 kHz is indicated by the subcarrier spacing indicatorbit then the modulation coding scheme MCS or TBS index would refer to adifferent set of values e.g. a different lookup table in thespecifications to that when 15 kHz is indicated. This embodiment isbased on the observation that fewer transport bits can be transportedper subcarrier using a 3.75 kHz numerology than for a 15 kHz numerology.

In another embodiment, no explicit bit is used but instead thesubcarrier spacing used is implicitly indicated by the MCS/TBS field.The MCS/TBS field typically points to an index of a MCS/TBS table andthis table would include entries that are only specific to single tone3.75 kHz transmission and entries that are only specific to single andmulti-tone 15 kHz transmissions. For example, the lowest X entries inthe MCS/TBS table are only applicable for 3.75 kHz transmission and soif one of these entries is indicated, then it would implicitly indicate3.75 kHz single tone transmission is used and the frequency resourcewould be interpreted for 48 subcarriers as per previous embodiment. Ifan entry other than one of the lowest X entries is used then thissignalling would implicitly indicate 15 kHz subcarrier spacing which canbe single tone or multi-tone.

Another method of determining whether the uplink transmission is basedon a 3.75 kHz subcarrier or a 15 kHz subcarrier is based on UEmeasurements of downlink channel quality. The UE measures the downlinkchannel quality, for example by performing a reference signal receivedpower RSRP measurement. Depending on the downlink channel quality, theUE chooses which set of PRACH resources to use, where different PRACHresources are associated with different coverage levels. Each set ofPRACH resources is associated with either single-tone or multi-tonetransmission for the first uplink message msg3 and with either a 3.75kHz subcarrier bandwidth or a 15 kHz subcarrier bandwidth. In thismethod, there would be no need to indicate a “single tone” bit in theNB-PDCCH that allocates resource for the uplink transmission. The UEwould reconfigure its NB-PDCCH decoding logic to interpret the NB-PDCCHaccording to whether the NB-PDCCH will allocate a 3.75 kHz uplinktransmission or a 15 kHz uplink transmission, for example the UEinterprets the “frequency resource field” of the NB-PDCCH depending onthe set of PRACH resources that is used. Indeed, in this case, theformat of the NB-PDCCH, for example the number of bits carried by theNB-PDCCH can be different depending on whether a 3.75 kHz uplinktransmission is allocated or a 15 kHz transmission is allocated. This isbecause, in this case, the UE knows a-priori what format of DCI (carriedby the NB-PDCCH) to decode: it does not need to blindly decode betweendifferent potential DCI formats.

Accordingly embodiments of the present technique can provide anarrangement for signalling efficiently different possible subcarrierspacings for which single or multiple tones are available, for example a3.75 kHz subcarrier spacing is only used for single tone transmissionand a 15 kHz subcarrier spacing is used for single tone and multi-tonetransmissions. Although this signalling can be achieved by using higherlayer protocols, such an implementation would reduce eNB schedulingflexibility.

Signalling a Dynamic TTI

In conventional LTE systems data is transmitted on both the uplink andthe downlink, by dividing the data into blocks, known as transportblocks (TB) and transmitted within a Transmission Time Interval (TTI).The TTI in LTE is fixed to 1 ms or one subframe. Thus the size of thetransport block is determined by the amount of data, which can betransmitted in a subframe. If a large Transport Block Size (TBS) needsto be transmitted, more frequency resources, in the form of PhysicalResource Blocks (PRB)s can be used, since the time resource is fixed (to1 ms).

FIG. 7 provides an illustration of a conventional arrangement in which atransport block is transmitted by downlink to a UE. FIG. 7 correspondsto the diagram shown in FIG. 2 and so like features have the samereferences and only the differences to FIG. 2 will be described.

As shown in FIG. 7 within a twelve subcarrier physical resource block(PRB) 208, an allocation is made for transmitting a transport block. Asshown in FIG. 7 the physical resource block 701 has a size correspondingto the twelve subcarriers of the subframe and transports a transportblock that is transmitted in one subframe. Accordingly, the transmissiontime interval, TTI, 702 is one millisecond corresponding to the subframeduration.

According to an example embodiment, which may find application toNB-IoT, a frequency resource available to a narrowband carrier islimited to one PRB. Furthermore frequency resource allocation to UEs canbe made as one or more of the twelve available subcarriers of the PRB.As such, where the frequency resource allocation is less than the fullPRB, then the Transport Block Size (TBS) must be adapted in accordancewith the number of subcarriers of the available twelve allocated to theUE. Therefore for transmissions which use less than one PRB, the numberof resource elements (REs) may not be sufficient to carry the desiredTBS. It is possible to segment a data packet into multiple smallertransport blocks to be carried in multiple subframe transmissions,however, each transmission incurs overheads and therefore segmentationleads to lower efficiency due to overhead signalling associated with thetransmission of each transport block. Hence in 3GPP, it is suggestedthat a transport block of the conventional size can be transmitted overmultiple subframes, which is illustrated in FIGS. 8 and 9.

As shown in FIGS. 8 and 9, a conventional transport block, which wouldbe transmitted in one LTE subframe is transmitted over n subframes,where n is a function of the number of subcarriers of the PRB allocatedfor the UE to transmit its data. As such the amount of data transmittedper subframe can be interpreted as a Basic Resource Unit (BRU), so thata Transport Block can be spread over multiple BRUs. The BRU consists ofBasic Frequency Resource (BFR) and Basic Time Resource (BTR). As shownin FIG. 9, the BTU for transmitting data remains the same and the TTIfor example can be a multiple of the BTR.

FIG. 8 provides a schematic block diagram illustrating an effect on theTTI of varying the number of subcarriers which are allocated to a UE totransmit or receive data. As shown in FIG. 8 four examples are providedillustrating how the length of the TTI changes between one, three, sixand twelve carriers.

FIG. 9 provides a schematic diagram illustrating how the differentnumbers of subcarriers varies the TTI. As shown in FIG. 9 a radio frame200 is shown which corresponds to the radio frame 200 shown in FIGS. 7and 2. According to the conventional example shown in FIG. 7 for an LTEwireless access interface, allocating twelve subcarriers or a physicalresource block allows the data of a conventional transport block size tobe transmitted within one subframe as shown in FIG. 7 and FIG. 8. Thetransport block 901 is shown in FIG. 9 to have a duration of TTI1 fortwelve allocated subcarriers. However, if the number of subcarriersallocated to the UE to receive data on the downlink is six subcarriers,then proportionally the length of the TTI must increase to twice thelength for the example where twelve subcarriers are allocated assumingthat the modulation and coding is the same. Therefore, as shown in FIG.9 the transport block 902 is transmitted over two BTRs 910, 912 using alonger TTI2 that has increased Correspondingly, if the number ofsubcarriers allocated to the UE is three as shown in the third example,then the transport block 920 would be transmitted over an even longerTTI length such as TTI3, which is the equivalent of four BTRs 930, 932,934, 936.

As will be appreciated from the above examples, the Basic FrequencyResource (BFR) is a single subcarrier. Hence, a Transport Block can betransmitted over multiple subcarriers.

There are two ways of interpreting the BTR which are:

-   -   The Basic Time Resource (in units of the number of subframes) is        dependent upon the number of subcarriers used. For example        BTR=12/(number of subcarriers), hence if 1 subcarrier is used,        BTR=12 subframes and if 12 subcarriers (i.e. entire PRB) are        used, BTR =1 subframe)    -   The BTR is fixed to a specific value regardless of the number of        subframe used

Since a Transport Block can be transmitted using multiple BRU and theBRU can extend in time and frequency, this suggested that the TTI isvariable. Therefore, there is a need to indicate the TTI used, or theBTR used for a specific transport block transmission.

According to the present technique there is provided an arrangement inwhich the TTI or BTR is implicitly or explicitly indicated in the DCI(grant). The signalling of the TTI or BTR as well as the frequencyresource used is signalled using for example the DCI for both uplinkresources granted and the downlink resources granted._The term TTI andnumber of BTR used refer to the same principle, that is, the number ofsubframes (or time resource) on which a transport block is transmitted.In the following paragraphs the term TTI is used because it is anexisting term used in LTE. As will be appreciated though from the abovediscussion, according to the example embodiments, the TTI is dynamicallyvariable as a function of the frequency resource allocated to the UE fortransmitting or receiving.

A part-schematic block diagram part-message flow diagram is shown inFIG. 10 illustrates example embodiments of the present technique. Asshown in FIG. 10 the UE 104 and eNB 101 are shown which correspond tothe UE and eNB illustrated in FIG. 4. However, in FIG. 10 the UE 104includes a data buffer 1001. In accordance with a conventionalarrangement and as illustrated in the second example 417 shown in FIG.4, a UE 104 may conventionally transmit a buffer status report 1002 tothe eNB. Accordingly, at some point, the eNB 101 transmits a DCI message1004 allocating resources of the UE on the uplink to transmit the datawithin its data buffer 1001. However, in accordance with the presenttechnique the DCI message 1004 includes a field 1006 providinginformation for the transmission of the data. In accordance with thepresent technique, the information in the field 1006 provides the UE 104with an indication of the TTI size it should use. The indication may bea new field or may be provided from information relating to thetransmission parameters which the UE should use, from which the TTI canbe inferred. The DCI may also include a field indicating the subcarrierspacing 1008 which may be used as explained for the embodimentsdescribed above to identify a subcarrier spacing which the UE shoulduse.

As will be appreciatd from the above embodiments the TTI can beindicated in the downlink grant to cover both uplink and downlinktransmissions. In the downlink grant, there is no need to indicatesubcarrier spacing. FIG. 10 is valid for the uplink grant.

As shown in FIG. 10 the data in the data buffer 1001 is carried by atransport block which has a size and is arranged for transmission forexample on three subcarriers which therefore requires that the TTI3should be used.

In a second example a DCI message 1020 which correspondingly includes afield 1022 identifying the subcarrier spacing and provides in a field1024 communications parameters for transmitting the data. As for theexample explained above, the field providing the communicationsparameters 1024 can implicitly or explicitly identify the TTI whichshould be used by the UE. In the second example 1030 the TTI is oflength TTI1 because twelve of the subcarriers of the available physicalresource block have been allocated for transmitting the data on theuplink to the eNB. Accordingly, as shown in the second example of FIG.10 the transport block is mapped to one subframe when the number ofsubcarriers allocated is equal to the maximum number which is availableto be a shorter duration of TTI 1.

As indicated above, in some embodiments, a new field is introduced inthe DCI which indicates the length of the TTI. The possible TTI lengthcan be predefined from either the absolute TTI length in terms of thenumber of subframes, or an index to a lookup table containing theallowed TTI length can be signalled in this new field.

In other embodiments, the TTI length is implicitly determined from themodulation and coding scheme (MCS). For a given number of subcarriersand a transport block size, an MCS with low coding rate would requiremore resources and in this case, more time resource and hence a longerTTI. Similarly an MCS with high coding rate would require less resourceand therefore a shorter TTI. In terms of BTR, more BTR will be used forlow code rate and vice versa for high code rate. The relationshipbetween the actual TTI length and MCS can be prespecified and so knownto both the UE and the eNB in the form of a lookup table, a formula orconfigured by higher layers.

In other embodiments, the TTI length is implicitly determined from theTransport Block Size (TBS). A larger TBS would require more resourcesand therefore for a given number of subcarriers, it would have a longerTTI. Similarly, a smaller TBS would require less resources and for agiven number of subcarriers would have a shorter TTI. The relationshipbetween TTI length and TBS can be prespecified and therefore known tothe UE and the eNB in advance, and may be represented in the form oflookup table or formula or configured by higher layers.

In another embodiment, the TTI length is implicitly determined by thenumber of subcarriers used. The smaller the number of subcarriers used,the longer the TTI to make up for the lack of resources in the frequencydomain. Similarly, the larger the number of subcarriers used, theshorter the TTI since more resources are available in the frequencydomain.

In other embodiments the number of “equivalent PRB” P_(E_PRB), isindicated in the DCI. It will be appreciated that in the current LTEsystem the number of PRB used is signalled and together with the MCSIndex, the TBS can be determined from a lookup table such as thatdisclosed in TS36.213 [4]. However, in NB-IoT only a single PRB is usedand therefore the “equivalent PRB” is a new indication of the amount ofresources required in terms of a fraction of the PRB. Since the numberof subcarriers in a PRB is known (i.e. 12×15 kHz subcarriers or 48×3.75kHz subcarriers), then the TTI in terms of the number of subframes canbe directly calculated from PE_(E_PRB) used. Therefore for a 15 kHzsubcarrier bandwidth:

${TTI} = \frac{12 \times P_{E\;\_\;{PRB}}}{N_{Subcarrier}}$

Where N_(Subcarrier) is the number of (15 kHz) subcarrier used. Forexample, the DCI indicates the MCS Index and P_(E_PRB), which would givethe TBS as shown in Table 6. If the MCS Index is 7 and the P_(E_PRB)=4,the TBS is 472 bits. Assume the N_(Subcarrier) is also signalled in theDCI and is set to 6 subcarriers, the TTI length (in number of 1 mssubframes) required to carry this transport block is therefore eightsubframes. It should be appreciated that P_(E_PRB) need not be aninteger, that is. some new TBS entries can be defined for a fraction ofa PRB. Other suitable terms can be used for P_(E_PRB), for exampleoverall resources required.

TABLE 6 Lookup table for TBS (bits) given the MCS index and Number ofequivalent PRBs MCS Number of equivalent PRBs, P_(E)_PRB Index 1 2 3 4 56  0  16  32  56  88 120  152  1  24  56  88 144 176  208  2  32  72 144176 208  256  3  40 104 176 208 256  328  4  56 120 208 256 328  408  5 72 144 224 328 424  504  6 328 176 256 392 504  600  7 104 224 328 472584  712  8 120 256 392 536 680  808  9 136 296 456 616 776  936 10 144328 504 680 872 1032

In another embodiment, the TTI length is implicitly determined by acombination of different variables defined above. That is the TTI lengthis determined by MCS, TBS and Nsubcarrier. That is if the equivalent PRBP_(E_PRB) is not indicated in the DCI, it can be derived from MCS andTBS (assuming TBS is signalled in the DCI) using a lookup table similarto that in Table 6. Once the P_(E_PRB) is derived the TTI length can beobtained using one of the above embodiments.

In another embodiment the TTI or BTR for a specific number ofsubcarriers is an integer multiple of a larger number of subcarriersdivided by the allocated number of subcarriers. An example is shown inFIG. 8, where there are 4 possible N_(Subcarrier)={1, 2, 6, 12}transmissions. The TTI (or BTR) of a smaller N_(Subcarrier) is aninteger multiple of that of a larger N_(Subcarrier). Here whenN_(Subcarrier)=1, TTI=12 subframes and when N_(Subcarrier)=62, TTI=6where 12 is integer multiple of 6. This allows UEs using differentsubcarriers to be aligned in time easily thereby simplifying theoperation of the scheduler to allocate the communications resource tothe NB-IoT UEs.

Annex 1:

The simplified structure of the downlink of an LTE wireless accessinterface presented in FIG. 2, also includes an illustration of eachsubframe 201, which comprises a control region 205 for the transmissionof control data, a data region 206 for the transmission of user data,reference signals 207 and synchronisation signals which are interspersedin the control and data regions in accordance with a predeterminedpattem. The control region 204 may contain a number of physical channelsfor the transmission of control data, such as a physical downlinkcontrol channel PDCCH, a physical control format indicator channelPCFICH and a physical HARQ indicator channel PHICH. The data region maycontain a number of physical channel for the transmission of data, suchas a physical downlink shared channel PDSCH and a physical broadcastchannels PBCH. Although these physical channels provide a wide range offunctionality to LTE systems, in terms of resource allocation and thepresent disclosure PDCCH and PDSCH are most relevant. Furtherinformation on the structure and functioning of the physical channels ofLTE systems can be found in [1].

Resources within the PDSCH may be allocated by an eNodeB to UEs beingserved by the eNodeB. For example, a number of resource blocks of thePDSCH may be allocated to a UE in order that it may receive data that ithas previously requested or data which is being pushed to it by theeNodeB, such as radio resource control RRC signalling. In FIG. 2, UE1has been allocated resources 208 of the data region 206, UE2 resources209 and UE resources 210. UEs in a an LTE system may be allocated afraction of the available resources of the PDSCH and therefore UEs arerequired to be informed of the location of their allocated resourceswithin the PDCSH so that only relevant data within the PDSCH is detectedand estimated. In order to inform the UEs of the location of theirallocated communications resources, resource control informationspecifying downlink resource allocations is conveyed across the PDCCH ina form termed downlink control information DCI, where resourceallocations for a PDSCH are communicated in a preceding PDCCH instancein the same subframe. During a resource allocation procedure, UEs thusmonitor the PDCCH for DCI addressed to them and once such a DCI isdetected, receive the DCI and detect and estimate the data from therelevant part of the PDSCH.

Each uplink subframe may include a plurality of different channels, forexample a physical uplink shared channel PUSCH 305, a physical uplinkcontrol channel PUCCH 306, and a physical random access channel PRACH.The physical Uplink Control Channel PUCCH may carry control informationsuch as ACK/NACK to the eNodeB for downlink transmissions, schedulingrequest indicators SRI for UEs wishing to be scheduled uplink resources,and feedback of downlink channel state information CSI for example. ThePUSCH may carry UE uplink data or some uplink control data. Resources ofthe PUSCH are granted via PDCCH, such a grant being typically triggeredby communicating to the network the amount of data ready to betransmitted in a buffer at the UE. The PRACH may be scheduled in any ofthe resources of an uplink frame in accordance with a one of a pluralityof PRACH patterns that may be signalled to UE in downlink signallingsuch as system information blocks. As well as physical uplink channels,uplink subframes may also include reference signals. For example,demodulation reference signals DMRS 307 and sounding reference signalsSRS 308 may be present in an uplink subframe where the DMRS occupy thefourth symbol of a slot in which PUSCH is transmitted and are used fordecoding of PUCCH and PUSCH data, and where SRS are used for uplinkchannel estimation at the eNodeB. Further information on the structureand functioning of the physical channels of LTE systems can be found in[1].

In an analogous manner to the resources of the PDSCH, resources of thePUSCH are required to be scheduled or granted by the serving eNodeB andthus if data is to be transmitted by a UE, resources of the PUSCH arerequired to be granted to the UE by the eNode B. At a UE, PUSCH resourceallocation is achieved by the transmission of a scheduling request or abuffer status report to its serving eNodeB. The scheduling request maybe made, when there is insufficient uplink resource for the UE to send abuffer status report, via the transmission of Uplink Control InformationUCI on the PUCCH when there is no existing PUSCH allocation for the UE,or by transmission directly on the PUSCH when there is an existing PUSCHallocation for the UE. In response to a scheduling request, the eNodeBis configured to allocate a portion of the PUSCH resource to therequesting UE sufficient for transferring a buffer status report andthen inform the UE of the buffer status report resource allocation via aDCI in the PDCCH. Once or if the UE has PUSCH resource adequate to senda buffer status report, the buffer status report is sent to the eNodeBand gives the eNodeB infoimation regarding the amount of data in anuplink buffer or buffers at the UE. After receiving the buffer statusreport, the eNodeB can allocate a portion of the PUSCH resources to thesending UE in order to transmit some of its buffered uplink data andthen inform the UE of the resource allocation via a DCI in the PDCCH.For example, presuming a UE has a connection with the eNodeB, the UEwill first transmit a PUSCH resource request in the PUCCH in the form ofa UCI. The UE will then monitor the PDCCH for an appropriate DCI,extract the details of the PUSCH resource allocation, and transmituplink data, at first comprising a buffer status report, and/or latercomprising a portion of the buffered data, in the allocated resources.

Although similar in structure to downlink subframes, uplink subframeshave a different control structure to downlink subframes, in particularthe upper 309 and lower 310 subcarriers/frequencies/resource blocks ofan uplink subframe are reserved for control signaling rather than theinitial symbols of a downlink subframe. Furthermore, although theresource allocation procedure for the downlink and uplink are relativelysimilar, the actual structure of the resources that may be allocated mayvary due to the different characteristics of the OFDM and SC-FDMinterfaces that are used in the downlink and uplink respectively. InOFDM each subcarrier is individually modulated and therefore it is notnecessary that frequency/subcarrier allocation are contiguous however,in SC-FDM subcarriers are modulation in combination and therefore ifefficient use of the available resources are to be made contiguousfrequency allocations for each UE are preferable.

As a result of the above described wireless interface structure andoperation, one or more UEs may communicate data to one another via acoordinating eNodeB, thus forming a conventional cellulartelecommunications system. Although cellular communications system suchas those based on the previously released LTE standards have beencommercially successful, a number of disadvantages are associated withsuch centralised systems. For example, if two UEs which are in closeproximity wish to communicate with each other, uplink and downlinkresources sufficient to convey the data are required. Consequently, twoportions of the system's resources are being used to convey a singleportion of data. A second disadvantage is that an eNodeB is required ifUEs, even when in close proximity, wish to communicate with one another.These limitations may be problematic when the system is experiencinghigh load or eNodeB coverage is not available, for instance in remoteareas or when eNodeBs are not functioning correctly.

Overcoming these limitations may increase both the capacity andefficiency of LTE networks but also lead to the creations of new revenuepossibilities for LTE network operators.

REFERENCES

-   [1] LTE for UMTS: OFDMA and SC-FDMA Based Radio Access, Harris Holma    and Antti Toskala, Wiley 2009, ISBN 978-0-470-99401-6.-   [2] RP-151621, “New Work Item: NarrowBand IOT NB-IOT,” Qualcomm,    RAN#69-   [3] R1-157783, “Way Forward on NB-IoT,” CMCC, Vodafone, Ericsson,    Huawei, HiSilicon, Deutsche Telekom, Mediatek, Qualcomm, Nokia    Networks, Samsung, Intel, Neul, CATR, AT&T, NTT DOCOMO, ZTE, Telecom    Italia, IITH, CEWiT, Reliance-Jio, CATT, u-blox, China Unicom, LG    Electronics, Panasonic, Alcatel-Lucent, Alcatel-Lucent Shanghai    Bell, China Telecom. RAN1#83-   [4] 3GPP TS36.213

The following numbered paragraphs provide further example aspects andfeatures of embodiments of the present technique:

Paragraph 1. A communications device configured to transmit signals toand/or receive signals from an infrastructure equipment of a mobilecommunications network, the communications device comprising

a receiver configured to receive signals transmitted by theinfrastructure equipment in accordance with a wireless access interface,

a transmitter configured to transmit signals to the infrastructureequipment in accordance with the wireless access interface, and

a controller configured to control the transmitter and the receiver totransmit data to the infrastructure equipment via an uplink of thewireless access interface or to receive data on the downlink of thewireless access interface, wherein the wireless access interface canprovide a plurality of different spacing of subcarriers for transmittingsignals representing the data on the uplink or for receiving the signalsrepresenting the data on the downlink, and the controller is configuredin a combination with the transmitter and the receiver

when the infrastructure equipment identifies a requirement to providecommunications resources of the wireless access interface on the uplinkfor the communications device to transmit data to the infrastructureequipment or on the downlink for the communications device to receivedata from the infrastructure equipment, to receive an indication on adownlink of the wireless access interface of one of the plurality ofdifferent subcarrier spacing which the communications device should useto transmit or to receive the signals representing the data, theindicated subcarrier spacing also determining whether the communicationsdevice should use a single subcarrier or multiple subcarriers.

Paragraph 2. A communications device according to paragraph 1, whereinthe receiver is configured to receive from the infrastructure equipmentan indication of which of the subcarriers of a plurality of availablesubcarriers, with the indicated subcarrier spacing, the communicationsdevice should use to transmit the data to the infrastructure equipmentor to receive the data from the infrastructure equipment or whichplurality of available subcarriers, with the indicated subcarrierspacing, the communications device should use to transmit or to receivethe data, depending on the indicated subcarrier spacing.

Paragraph 3. A communications device according to paragraph 2, whereinthe receiver is configured to receive the indication of the subcarrierspacing with the indication of the subcarrier or multiple subcarriers touse in a downlink control message comprising a field indicating thesubcarrier spacing and a field indicating the subcarrier or multiplesubcarriers to use, and the controller is configured to interpretdifferently the field indicating which of the subcarrier or multiplesubcarriers to use depending upon whether the field indicating thesubcarrier spacing indicates a subcarrier spacing which can only be usedas a single subcarrier or a subcarrier spacing which can be used as asingle or multiple subcarriers.

Paragraph 4. A communications device according to paragraph 3, whereinthe field indicating which of the subcarrier or multiple subcarriers touse as a function of the subcarrier spacing is predetermined between theinfrastructure equipment and the communications device, which can berepresented as a table.

Paragraph 5. A communications device according to paragraph 4, whereinthe predetermined interpretation of the field indicating which of thesubcarrier or multiple subcarriers to use as a function of thesubcarrier spacing is received from the infrastructure equipment as partof broadcast system information.

Paragraph 6. A communications device according to paragraph 3, whereinthe downlink control message includes an indication of one or more of amodulation scheme to be used, a coding scheme to be used and a transportblock size to be used by the communications device when transmitting thedata, and the controller is configured to interpret the indication ofone or more of the modulation scheme, the coding scheme and thetransport block size to use differently depending on the indicatedsubcarrier spacing.

Paragraph 7. A communications device according to paragraph 6, whereinthe different interpretation of the indication of one or more of themodulation scheme, the coding scheme and the transport block sizedepending on the indicated subcarrier spacing is received from theinfrastructure equipment as part of broadcast system information.

Paragraph 8. A communications device according to paragraphs 1 to 7,wherein the controller is configured with the transmitter and thereceiver to measure a strength of signals received from theinfrastructure equipment via the wireless access interface, and

to transmit a report of the measurements to the infrastructureequipment, the infrastructure equipment selecting the subcarrier spacingfor the communications device based on the received measurement report.

Paragraph 9. A communications device according to paragraphs 3 to 8,wherein the downlink control message is transmitted as part of a randomaccess procedure.

Paragraph 10. A communications device according to paragraphs 1 to 10,wherein the plurality of different spacing of the subcarriers comprisestwo subcarrier spacing of 3.75 kHz and 15 kHz, and the indication of the3.75 kHz subcarrier spacing indicates that the communications deviceshould transmit the signals representing the data or receive the signalsrepresenting the data on a single subcarrier, and the indication of the15 kHz subcarrier indicates that the communications device shouldtransmit the signals representing the data or receive the signalsrepresenting the data on a single subcarrier or multiple subcarriers.

Paragraph 11. A communications device configured to transmit signals toand/or receive signals from an infrastructure equipment of a mobilecommunications network, the communications device comprising

a receiver configured to receive signals transmitted by theinfrastructure equipment in accordance with a wireless access interface,

a transmitter configured to transmit signals to the infrastructureequipment in accordance with the wireless access interface, and

a controller configured to control the transmitter and the receiver totransmit data to the infrastructure equipment via an uplink of thewireless access interface or to receive data on the downlink of thewireless access interface, wherein the wireless access interface canprovide a plurality of different spacing of subcarriers for transmittingsignals representing the data on the uplink or for receiving the signalsrepresenting the data on the downlink, and the controller is configuredin a combination with the transmitter and the receiver

to select one of a predetermined set of preambles to represent asubcarrier spacing requested by the communications device and a requestfor a single subcarrier or for multiple subcarriers,

to transmit as part of a random access procedure the preamble to theinfrastructure equipment representing the requested carrier spacing, and

to configured one of the transmitter to transmit the data on the uplinkor the receiver to receive the data on the downlink in accordance withthe requested subcarrier spacing.

Paragraph 12. A communications device according to paragraph 11, whereinthe controller is configured to select one of the predetermined set ofpreambles to represent the requested subcarrier spacing and a requestfor a single subcarrier or for multiple subcarriers depending on thesubcarrier spacing requested.

Paragraph 13. A communications device according to paragraph 11 or 12,wherein the controller is configured with the transmitter and thereceiver

to receive a downlink control message allocating communicationsresources of the uplink or the downlink, the downlink control messageincluding a field indicating frequency resources allocated by theinfrastructure equipment on the uplink or the downlink, the controllerbeing configured to interpret differently the field indicating thefrequency resources allocated by the infrastructure equipment accordingto the subcarrier spacing requested by the communications device.

Paragraph 14. A communications device according to paragraphs 11 to 13,wherein the controller is configured with the transmitter and thereceiver to measure a strength of signals received from theinfrastructure equipment via the wireless access interface, and

to identify the requested subcarrier spacing base on the strength of thesignals received from the infrastructure equipment.

Paragraph 15. A communications device according to paragraphs 11 to 14,wherein the plurality of different spacing of the subcarriers comprisestwo subcarrier spacing of 3.75 kHz and 15 kHz, and the indication of the3.75 kHz subcarrier spacing indicates that the communications deviceshould transmit the signals representing the data or receive the signalsrepresenting the data on a single subcarrier, and the indication of the15 kHz subcarrier indicates that the communications device shouldtransmit the signals representing the data or receive the signalsrepresenting the data on a single subcarrier or multiple subcarriers.

Paragraph 16. A method of communicating data to or from a communicationsdevice via a mobile communications network, the method comprising

transmitting signals representing data from the communications device toan infrastructure equipment forming part of a mobile communicationsnetwork via an uplink of a wireless access interface provided by theinfrastructure equipment, or

receiving signals representing data at the communications device from aninfrastructure equipment via a downlink of the wireless accessinterface, wherein the wireless access interface can provide a pluralityof different spacing of subcarriers for transmitting signalsrepresenting the data on the uplink or for receiving the signalsrepresenting the data on the downlink, and the transmitting or thereceiving includes

when the infrastructure equipment identifies a requirement to providecommunications resources of a wireless access interface on the uplink oron the downlink

receiving an indication on a downlink of the wireless access interfaceof one of the plurality of different subcarrier spacing which thecommunications device should use to transmit or to receive the signalsrepresenting the data, the indicated subcarrier spacing also determiningwhether the communications device should use a single subcarrier ormultiple subcarriers.

Paragraph 17. A method of communicating data to or from a communicationsdevice via a mobile communications network, the method comprising

transmitting signals representing data from the communications device toan infrastructure equipment forming part of a mobile communicationsnetwork via an uplink of a wireless access interface provided by theinfrastructure equipment, or

receiving signals representing data at the communications device from aninfrastructure equipment via a downlink of the wireless accessinterface, wherein the wireless access interface can provide a pluralityof different spacing of subcarriers for transmitting signalsrepresenting the data on the uplink or for receiving the signalsrepresenting the data on the downlink, and the transmitting or thereceiving includes

selecting one of a predetermined set of preambles to represent asubcarrier spacing requested by the communications device,

transmitting as part of a random access procedure the preamble to theinfrastructure equipment representing the requested carrier spacing, and

transmitting the data on the uplink or the receiving the data on thedownlink in accordance with the requested subcarrier spacing.

Paragraph 18. An infrastructure equipment forming part of a mobilecommunications network for transmitting signals to or receiving signalsfrom communications devices, the infrastructure equipment comprising

a transmitter configured to transmit signals to one or more of thecommunications devices in accordance with a wireless access interfaceformed by the infrastructure equipment, and

a receiver configured to receive signals transmitted by one or more ofthe communications devices in accordance with the wireless accessinterface,

a controller configured to control the transmitter and the receiver totransmit data to one or more of the communications devices via an uplinkof the wireless access interface or receive data from the one or morecommunications devices via a downlink of the wireless access interface,wherein the wireless access interface is provided with a plurality ofdifferent spacing of subcarriers for receiving signals representing thedata on an uplink from the one or more communications devices or fortransmitting signals representing the data on a downlink to the one ormore communications devise, and the controller is configured in acombination with the transmitter and the receiver

to identify a requirement to provide communications resources of thewireless access interface to one of the communications devices on theuplink or on the downlink,

to select one of the plurality of different subcarrier spacing, theselected subcarrier spacing also determining whether the communicationsdevice should use a single subcarrier or multiple subcarriers, and

to transmit an indication on a downlink of the wireless access interfaceof one of the plurality of different subcarrier spacing which thecommunications device should use to transmit or to receive the signalsrepresenting the data, the indicated subcarrier spacing also identifyingwhether the communications device should use a single subcarrier ormultiple subcarriers. Paragraph 19. An infrastructure equipmentaccording to paragraph 18, wherein the controller is configured with thetransmitter to transmit to the communications device an indication ofwhich of the subcarriers of a plurality of available subcarriers, withthe indicated subcarrier spacing, the communications device should useto transmit signals or to receive signals representing the data or whicha plurality of available subcarriers, with the indicated subcarrierspacing, the communications device should use to transmit signals or toreceive signals representing the data, depending on the indicatedsubcarrier spacing.

Paragraph 20. An infrastructure equipment according to paragraph 19,wherein the controller is configured with the transmitter to transmit tothe communications device the indication of the subcarrier spacing withthe indication of the subcarrier or multiple subcarriers to use in adownlink control message comprising a field indicating the subcarrierspacing and a field indicating the subcarrier or multiple subcarriers touse, and the controller is configured to select the field indicatingwhich of the subcarrier or multiple subcarriers to use differentlydepending upon whether the field indicating the subcarrier spacingindicates a subcarrier spacing which can only be used as a singlesubcarrier or a subcarrier spacing which can be used as a singlesubcarrier or multiple subcarriers.

Paragraph 21. An infrastructure equipment according to paragraph 20,wherein the field indicating which of the subcarrier or multiplesubcarriers to use as a function of the subcarrier spacing ispredetermined between the infrastructure equipment and thecommunications device, which can be represented as a table.

Paragraph 22. An infrastructure equipment according to paragraph 20,wherein the controller is configured with the transmitter to transmitthe interpretation of the field indicating which of the subcarrier ormultiple subcarriers to use as a function of the subcarrier as part ofbroadcast system information.

Paragraph 23. An infrastructure equipment according to paragraphs 18 to22, wherein the downlink control message includes an indication of oneor more of a modulation scheme to be used, a coding scheme to be usedand a transport block size to be used by the communications device whentransmitting the data, and the controller is configured to set theindication of one or more of the modulation scheme, the coding schemeand the transport block size to use differently depending on theindicated subcarrier spacing.

Paragraph 24. An infrastructure equipment according to paragraph 23,wherein the controller in combination with the transmitter is configuredto transmit the different interpretation of the indication of one ormore of the modulation scheme, the coding scheme and the transport blocksize depending on the indicated subcarrier spacing as part of broadcastsystem information.

Paragraph 25. An infrastructure equipment according to paragraphs 13 to19, wherein the controller is configured with the transmitter and thereceiver

to receive a measurement report from the communications device, themeasurement report providing an indication of a strength of signalsreceived by the communications device from the infrastructure equipmentvia the wireless access interface, and

to select the subcarrier spacing for the communications device based onthe received measurement report.

Paragraph 26. An infrastructure equipment according to paragraphs 18 to25, wherein the downlink control message is a resource allocationmessage transmitted as part of a random access procedure.

Paragraph 27. An infrastructure equipment according to paragraphs 18 to26, wherein the plurality of different spacing of the subcarrierscomprises two subcarrier spacing of 3.75 kHz and 15 kHz, and theindication of the 3.75 kHz subcarrier spacing indicates that thecommunications device should transmit the signals or receive the signalsrepresenting the data on a single subcarrier, and the indication of the15 kHz subcarrier indicates that the communications device shouldtransmit the signals representing the data or receive the signalsrepresenting the data on a single subcarrier or on multiple subcarriers.

Paragraph 28. An infrastructure equipment forming part of a mobilecommunications network for transmitting signals to or receiving signalsfrom communications devices, the infrastructure equipment comprising

a transmitter configured to transmit signals to one or more of thecommunications devices in accordance with a wireless access interfaceformed by the infrastructure equipment, and

a receiver configured to receive signals transmitted by one or more ofthe communications devices in accordance with the wireless accessinterface,

a controller configured to control the transmitter and the receiver totransmit data to one or more of the communications devices via an uplinkof the wireless access interface or receive data from the one or morecommunications devices via a downlink of the wireless access interface,wherein the wireless access interface is provided with a plurality ofdifferent spacing of subcarriers for receiving signals representing thedata on an uplink from the one or more communications devices or fortransmitting signals representing the data on a downlink to the one ormore communications devise, and the controller is configured in acombination with the transmitter and the receiver

to receive a preamble from one of the communications devices as part ofa random access procedure requesting communications resources of thewireless access interface on the uplink or on the downlink, using one ofthe plurality of different subcarrier spacing, the selected subcarrierspacing also determining whether the communications device should use asingle subcarrier or multiple subcarriers, and

to transmit signals on the downlink or to receive signals on the uplinkin accordance with the requested carrier spacing.

Paragraph 29. A method of transmitting data from an infrastructureequipment forming part of a mobile communications network to acommunications device, or receiving data at the infrastructure equipmentfrom a communications device, the method comprising

transmitting signals representing the data to the communications devicein accordance with a wireless access interface formed by theinfrastructure equipment on a downlink of the wireless access interface,or

receiving signals representing the data transmitted by thecommunications device in accordance with the wireless access interface,wherein the wireless access interface is provided with a plurality ofdifferent spacing of subcarriers for transmitting the signalsrepresenting the data on a downlink of the wireless access interface toone or more of the communications devices or receiving the signalsrepresenting the data on an uplink from the one or more communicationsdevices, and the transmitting or the receiving includes

selecting one of the plurality of different subcarrier spacing, theselected subcarrier spacing also determining whether the communicationsdevice should use a single subcarrier or multiple subcarriers, and

transmitting an indication on a downlink of the wireless accessinterface of one of the plurality of different subcarrier spacing whichthe communications device should use to transmit the signalsrepresenting the data or to receive the signals representing the data,the indicated subcarrier spacing also identifying whether thecommunications device should use a single subcarrier or multiplesubcarriers.

Paragraph 30. A method of transmitting data from an infrastructureequipment forming part of a mobile communications network to acommunications device, or receiving data at the infrastructure equipmentfrom a communications device, the method comprising

transmitting signals representing the data to the communications devicein accordance with a wireless access interface formed by theinfrastructure equipment on a downlink of the wireless access interface,or

receiving signals representing the data transmitted by thecommunications device in accordance with the wireless access interface,wherein the wireless access interface is provided with a plurality ofdifferent spacing of subcarriers for transmitting the signalsrepresenting the data on a downlink of the wireless access interface toone or more of the communications devices or receiving the signalsrepresenting the data on an uplink from the one or more communicationsdevices, and the transmitting or the receiving includes

to receive a preamble from one of the communications devices as part ofa random access procedure requesting communications resources of thewireless access interface on the uplink or on the downlink, using one ofthe plurality of different subcarrier spacing, the selected subcarrierspacing also determining whether the communications device should use asingle subcarrier or multiple subcarriers, and

to transmit signals on the downlink or to receive signals on the uplinkin accordance with the requested carrier spacing.

Paragraph 31. Circuitry for a communications device for transmittingsignals to and/or receiving signals from an infrastructure equipment ofa mobile communications network, the circuitry comprising

receiver circuitry configured to receive signals transmitted by theinfrastructure equipment in accordance with a wireless access interface,

transmitter circuitry configured to transmit signals to theinfrastructure equipment in accordance with the wireless accessinterface, and

controller circuitry configured to control the transmitter and thereceiver to transmit data to the infrastructure equipment via an uplinkof the wireless access interface or to receive data on the downlink ofthe wireless access interface, wherein the wireless access interface canprovide a plurality of different spacing of subcarriers for transmittingsignals representing the data and the controller circuitry is configuredin a combination with the transmitter circuitry and the receivercircuitry

when the infrastructure equipment identifies a requirement to providecommunications resources of the wireless access interface on the uplinkfor the communications device to transmit data to the infrastructureequipment or on the downlink for the communications device to receivedata from the infrastructure equipment, to receive an indication on adownlink of the wireless access interface of one of the plurality ofdifferent subcarrier spacing which the communications device should useto transmit or to receive the signals representing the data, theindicated subcarrier spacing also determining whether the communicationsdevice should use a single subcarrier or multiple subcarriers.

Paragraph 32. Circuitry for an infrastructure equipment forming part ofa communications network, the circuitry comprising

transmitter circuitry configured to transmit signals to one or more ofthe communications devices in accordance with a wireless accessinterface formed by the infrastructure equipment, and

receiver circuitry configured to receive signals transmitted by one ormore of the communications devices in accordance with the wirelessaccess interface, controller circuitry configured to control thetransmitter and the receiver to transmit data to one or more of thecommunications devices via an uplink of the wireless access interface orreceive data from the one or more communications devices via a downlinkof the wireless access interface, wherein the wireless access interfaceis provided with a plurality of different spacing of subcarriers forreceiving signals representing the data on an uplink from the one ormore communications devices or for transmitting signals representing thedata on a downlink to the one or more communications devise, and thecontroller circuitry is configured in a combination with the transmittercircuitry and the receiver circuitry

to identify a requirement to provide communications resources of thewireless access interface to one of the communications devices on theuplink or on the downlink, to select one of the plurality of differentsubcarrier spacing, the selected subcarrier spacing also determiningwhether the communications device should use a single subcarrier ormultiple subcarriers, and

to transmit an indication on a downlink of the wireless access interfaceof one of the plurality of different subcarrier spacing which thecommunications device should use to transmit or to receive the signalsrepresenting the data, the indicated subcarrier spacing also identifyingwhether the communications device should use a single subcarrier ormultiple subcarriers.

Paragraph 33. A wireless communications network including aninfrastructure equipment according to paragraphs 18 to 28.

Paragraph 34. A communications device configured to transmit signals toand/or receive signals from an infrastructure equipment of a mobilecommunications network, the communications device comprising

a receiver configured to receive signals transmitted by theinfrastructure equipment in accordance with a wireless access interface,

a transmitter configured to transmit signals to the infrastructureequipment in accordance with the wireless access interface, and

a controller configured to control the transmitter and the receiver totransmit data to the infrastructure equipment via an uplink of thewireless access interface or to receive data on the downlink of thewireless access interface, wherein the wireless access interfaceincludes communications resources for allocation to the communicationsdevice on the uplink and the downlink, the communications resourcescomprising frequency resources of a predetermined number of subcarriers,one or more of which can be allocated to the communications device, andtime resources in which the wireless access interface is divided intopredetermined time units and the controller is configured in acombination with the transmitter and the receiver

when the infrastructure equipment identifies a requirement to providecommunications resources of the wireless access interface on the uplinkor on the downlink, to receive an indication on a downlink of thewireless access interface of one or more of the subcarriers allocated tothe communications device for receiving or transmitting the data, and atransmission time interval representing a number of the time unitswithin which a transport block of the data is to be transmitted or to bereceived, and the transmission time interval can vary as a number of thetime units.

Paragraph 35. A communications device according to paragraph 34, whereinthe receiver is configured to receive the indication of the one or moreof the subcarriers allocated to the communications device for receivingor transmitting the data, and the transmission time interval in adownlink control message which includes a field indicating the allocatedtransmission time interval.

Paragraph 36. A communications device according to paragraph 26 whereinthe downlink control message includes an indication of one or more of amodulation scheme to be used, a coding scheme to be used and a transportblock size to be used, and the controller is configured to interpret theindication of one or more of the modulation scheme, the coding schemeand the transport block size with the number of the one or moresubcarriers allocated to determine the transmission time interval.

Paragraph 37. A communications device according to paragraph 36, whereinthe downlink control message includes an indication of an index of amodulation and a coding scheme to be used and an equivalent number ofphysical resource blocks, and the controller is configured to interpretthe indication of the modulation and coding scheme and the equivalentnumber of physical resource blocks to determine a transport block size,and in combination with the number of the one or more subcarriersallocated to determine the transmission time interval.

Paragraph 38. A communications device according to paragraphs 35 to 37,wherein the transmission time interval is an integer multiple of thetime unit and the number of the one or more subcarriers which can beallocated by the infrastructure equipment divided by the allocatednumber of subcarriers.

Paragraph 39. A communications device according to paragraphs 35 to 38,wherein the transmission time interval varyies as a function of thenumber of the one or more subcarriers allocated to the communicationsdevice for transmitting or receiving.

Paragraph 40. A communications device according to paragraphs 34 to 39,wherein the downlink control message forms part of a resource allocationmessage or a random access response message.

Paragraph 41. A method of communicating data to or from a communicationsdevice via a mobile communications network, the method comprising

transmitting signals representing data from the communications device toan infrastructure equipment forming part of a mobile communicationsnetwork via an uplink of a wireless access interface provided by theinfrastructure equipment, or

receiving signals representing data at the communications device from aninfrastructure equipment via a downlink of the wireless accessinterface, wherein the transmitting or the receiving includes

when the infrastructure equipment identifies a requirement to providecommunications resources of a wireless access interface on the uplink oron the downlink, receiving an indication on a downlink of the wirelessaccess interface of

one or more of the subcarriers allocated to the communications devicefor transmitting or receiving the data, and

a transmission time interval representing a number of the time unitswithin which a transport block of the data is to be transmitted or to bereceived, the transmission time interval varying as a number of the timeunits.

Paragraph 42. A method according to paragraph 41, wherein thetransmission time interval varying as a number of the time unitscomprises varying the transmission time interval as a function of thenumber of the one or more subcarriers allocated to the communicationsdevice for transmitting or receiving.

Paragraph 43. An infrastructure equipment forming part of a mobilecommunications network for transmitting signals to or receiving signalsfrom communications devices, the infrastructure equipment comprising

a transmitter configured to transmit signals to one or more of thecommunications devices in accordance with a wireless access interfaceformed by the infrastructure equipment, and

a receiver configured to receive signals transmitted by one or more ofthe communications devices in accordance with the wireless accessinterface, a controller configured to control the transmitter and thereceiver to transmit data to one or more of the communications devicesor receive data from the one or more communications devices via thewireless access interface, wherein the wireless access interfaceincludes communications resources for allocation to the communicationsdevice on the uplink and the downlink, the communications resourcescomprising frequency resources of a predetermined number of subcarriers,one or more of which can be allocated to the communications device, andtime resources in which the wireless access interface is divided intopredetermined time units and the controller is configured in acombination with the transmitter and the receiver

to identify a requirement to provide communications resources of thewireless access interface to one of the communications devices on theuplink or on the downlink,

to determine a number of the subcarriers of the wireless accessinterface to be allocated to the communications device, and

to determine a transmission time interval for transmitting data to orreceiving data from the communications device as a function of thenumber of the one or more subcarriers allocated to the communicationsdevice, and

to transmit an indication on a downlink of the wireless access interfaceof the one or more subcarriers allocated to the communications devicefor receiving or transmitting the data, and the transmission timeinterval representing a number of the time units within which atransport block of the data is to be transmitted or to be received, thetransmission time interval varying as a number of the time units.

Paragraph 44. A method of transmitting data from an infrastructureequipment forming part of a mobile communications network to acommunications device, or receiving data at the infrastructure equipmentfrom a communications device, the method comprising

transmitting signals representing the data to the communications devicein accordance with a wireless access interface formed by theinfrastructure equipment on a downlink of the wireless access interface,or

receiving signals representing the data transmitted by thecommunications device in accordance with the wireless access interface,wherein the wireless access interface includes communications resourcesfor allocation to the communications device on the uplink and thedownlink, the communications resources comprising frequency resources ofa predetermined number of subcarriers, one or more of which can beallocated to the communications device, and time resources in which thewireless access interface is divided into predetermined time units andthe transmitting or the receiving the signals representing the dataincludes

identifying a requirement to provide communications resources of thewireless access interface to one of the communications devices on theuplink or on the downlink,

determining a number of the subcarriers of the wireless access interfaceto be allocated to the communications device, and

determining a transmission time interval for transmitting data to orreceiving data from the communications device as a function of thenumber of the one or more subcarriers allocated to the communicationsdevice, and

transmitting an indication on a downlink of the wireless accessinterface of the one or more subcarriers allocated to the communicationsdevice for receiving or transmitting the data, and the transmission timeinterval representing a number of the time units within which atransport block of the data is to be transmitted or to be received, thetransmission time interval varying as a number of the time units.

The invention claimed is:
 1. An infrastructure equipment forming part ofa mobile communications network for transmitting signals to or receivingsignals from communications devices, the infrastructure equipmentcomprising: a transmitter configured to transmit signals to one or moreof the communications devices in accordance with a wireless accessinterface formed by the infrastructure equipment; a receiver configuredto receive signals transmitted by one or more of the communicationsdevices in accordance with the wireless access interface; and acontroller configured to control the transmitter and the receiver totransmit data to one or more of the communications devices via adownlink of the wireless access interface or receive data from the oneor more communications devices via an uplink of the wireless accessinterface, wherein the wireless access interface is provided with aplurality of different spacing of subcarriers for receiving signalsrepresenting the data on an uplink from the one or more communicationsdevices or for transmitting signals representing the data on a downlinkto the one or more communications devices, and the controller isconfigured in a combination with the transmitter and the receiver toidentify a requirement to provide communications resources of thewireless access interface to one of the communications devices on theuplink or on the downlink, to select one of the plurality of differentsubcarrier spacing, the selected subcarrier spacing also determiningwhether the communications device should use a single subcarrier ormultiple subcarriers, and to transmit an indication on a downlink of thewireless access interface of one of the plurality of differentsubcarrier spacing which the communications device should use totransmit or to receive the signals representing the data, the indicatedsubcarrier spacing also identifying whether the communications deviceshould use a single subcarrier or multiple subcarriers.
 2. Theinfrastructure equipment of claim 1, wherein the controller isconfigured with the transmitter to transmit to the communications devicean indication of which of the subcarriers of a plurality of availablesubcarriers, with the indicated subcarrier spacing, the communicationsdevice should use to transmit signals or to receive signals representingthe data or which a plurality of available subcarriers, with theindicated subcarrier spacing, the communications device should use totransmit signals or to receive signals representing the data, dependingon the indicated subcarrier spacing.
 3. The infrastructure equipment ofclaim 2, wherein the controller is configured with the transmitter totransmit to the communications device the indication of the subcarrierspacing with the indication of the subcarrier or multiple subcarriers touse in a. downlink control message comprising a field indicating thesubcarrier spacing and a field indicating the subcarrier or multiplesubcarriers to use, and the controller is configured to select the fieldindicating which of the subcarrier or multiple subcarriers to usedifferently depending upon whether the field indicating the subcarrierspacing indicates a subcarrier spacing which can only be used as asingle subcarrier or a subcarrier spacing which can be used as a singlesubcarrier or multiple subcarriers.
 4. The infrastructure equipment ofclaim 3, wherein the field indicating which of the subcarrier ormultiple subcarriers to use as a function of the subcarrier spacing ispredetermined between the infrastructure equipment and thecommunications device, which can be represented as a table.
 5. Theinfrastructure equipment of claim 3, wherein the controller isconfigured with the transmitter to transmit the interpretation of thefield indicating which of the subcarrier or multiple subcarriers to useas a function of the subcarrier as part of broadcast system information.6. The infrastructure equipment of claim 1, wherein the downlink controlmessage includes an indication of one or more of a modulation scheme tobe used, a coding scheme to be used and a transport block size to beused by the communications device when transmitting the data, and thecontroller is configured to set the indication of one or more of themodulation scheme, the coding scheme and the transport block size to usedifferently depending on the indicated subcarrier spacing.
 7. Theinfrastructure equipment of claim 6, wherein the controller incombination with the transmitter is configured to transmit the differentinterpretation of the indication of one or more of the modulationscheme, the coding scheme and the transport block size depending on theindicated subcarrier spacing as part of broadcast system information. 8.The infrastructure equipment of claim 1, wherein the controller isconfigured with the transmitter and the receiver to receive ameasurement report from the communications device, the measurementreport providing an indication of a strength of signals received by thecommunications device from the infrastructure equipment via the wirelessaccess interface, and to select the subcarrier spacing for thecommunications device based on the received measurement report.
 9. Theinfrastructure equipment of claim 1, wherein the downlink controlmessage is a resource allocation message transmitted as part of a randomaccess procedure.
 10. The infrastructure equipment of claim 1, whereinthe plurality of different spacing of the subcarriers comprises twosubcarrier spacing of 3.75 kHz and 15 kHz, and the indication of the3.75 kHz subcarrier spacing indicates that the communications deviceshould transmit the signals or receive the signals representing the dataon a single subcarrier, and the indication of the 15 kHz subcarrierindicates that the communications device should transmit the signalsrepresenting the data or receive the signals representing the data on asingle subcarrier or on multiple subcarriers.
 11. An infrastructureequipment forming part of a mobile communications network fortransmitting signals to or receiving signals from communicationsdevices, the infrastructure equipment comprising: a transmitterconfigured to transmit signals to one or more of the communicationsdevices in accordance with a wireless access interface formed by theinfrastructure equipment; a receiver configured to receive signalstransmitted by one or more of the communications devices in accordancewith the wireless access interface; and a controller configured tocontrol the transmitter and the receiver to transmit data to one or moreof the communications devices via a downlink of the wireless accessinterface or receive data from the one or more communications devicesvia an uplink of the wireless access interface, wherein the wirelessaccess interface is provided with a plurality of different spacing ofsubcarriers for receiving signals representing the data on an uplinkfrom the one or more communications devices or for transmitting signalsrepresenting the data on a downlink to the one or more communicationsdevices, and the controller is configured in a combination with thetransmitter and the receiver to receive a preamble from one of thecommunications devices as part of a random access procedure requestingcommunications resources of the wireless access interface on the uplinkor on the downlink, using one of the plurality of different subcarrierspacing, the selected subcarrier spacing also determining whether thecommunications device should use a single subcarrier or multiplesubcarriers, and to transmit signals on the downlink or to receivesignals on the uplink in accordance with the requested carrier spacing.12. Circuitry for an infrastructure equipment forming part of acommunications network, the circuitry comprising: transmitter circuitryconfigured to transmit signals to one or more of the communicationsdevices in accordance with a wireless access interface formed by theinfrastructure equipment; receiver circuitry configured to receivesignals transmitted by one or more of the communications devices inaccordance with the wireless access interface; and controller circuitryconfigured to control the transmitter and the receiver to transmit datato one or more of the communications devices via a downlink of thewireless access interface or receive data from the one or morecommunications devices via an uplink of the wireless access interface,wherein the wireless access interface is provide with a plurality ofdifferent spacing of subcarriers for receiving signals representing thedata on an uplink from the one or more communications devices or fortransmitting signals representing the data on a downlink to the one ormore communications devices, and the controller circuitry is configuredin a combination with the transmitter circuitry and the receivercircuitry to identify a requirement to provide communications resourcesof the wireless access interface to one of the communications devices onthe uplink or on the downlink, to select one of the plurality ofdifferent subcarrier spacing, the selected subcarrier spacing alsodetermining whether the communications device should use a singlesubcarrier or multiple subcarriers, and to transmit an indication on adownlink of the wireless access interface of one of the plurality ofdifferent subcarrier spacing which the communications device should useto transmit or to receive the signals representing the data, theindicated subcarrier spacing also identifying whether the communicationsdevice should use a single subcarrier or multiple subcarriers.